Lighting fixture closure



March 2, 1943. J." DONNELLY 2,312,393

LIGHTING FIXTURE CLOSURE} Filed Feb. 24, 1941 INVENTOR MAMA; Dam/a0 BY ATTORNEY Patented Mar. 2, 1943 LIGHTING FIXTURE CLOSURE James Donnelly, Meriden, Conn, assignor to T h e Miller Company, Meriden, Gonn., a corporation of Connecticut Application February 24, 1941, Serial No. 380,138

3 Claims.

The present invention relates to lighting fixture closures, and is more particularly directed toward lighting fixture closures for use with lighting equipment of substantial dimension, such as fluorescent lighting equipment.

In order to reduce the brightness of direct lighting fluorescent lighting equipment it is desirable to use diffusing screens below the lamps and in many cases these screens are made of sheet plastic extending the full length of the fixture and it is desirable to support the screening material in some form of metal frame of sufficient rigidity to be readily secured to the fixture and hold the sheet plastic in place. The use of rigid frames to which the sheet plasticis directly secured has proven unsatisfactory for the metal and plastic tend to change size and shape at different rates, setting up shrinkage strains likely to crack the plastic or to cause buckling and distortion which destroys or impairs the lines and appearance of the closure.

The present invention contemplates the provision of improved closures for the purpose wherein the diffusing plastic sheet is securely held in place in such a manner that it can freely stretch or shrink relative to the metal frame.

According to the preferred embodiment the edges of the plastic sheet are slidably received in grooved metal strips and the plastic sheets carry sheet metal clips adapted to slide along flanges carried by the sheet metal strips. These parts cooperate so that the sheet can move freely lengthwise of the frame member and is supported by the frame member.

The accompanying drawing shows, for purposes of illustrating the present invention, one of the many embodiments in which the invention may take form, it being understood that the drawing is illustrative of the invention rather than limiting the same.

In the drawing:

Figure 1 is a perspective view illustrating a lighting fixture closure;

Figure 2 is a perspective view illustrating the plastic sheet and clip; and

Figure 3 is a sectional view on the line 3-3 of Figure 1.

For purposes of illustration the screen H1 is here indicated as having vertical walls II and bottom wall 12. The shape of the screen, however, forms no part of the present invention and it may be shaped to fit in with the design of the fixture. The screen is provided with straight edges indicated at l3, l3.

Disposed at intervals along the edges of the screen material are clips such as indicated at M. These clips may be made of a piece of sheet metal folded, as indicated at I5, l5, to receive the plastic material It] and may be secured to it by punching in the sheet metal as indicated at 16. The sheet metal clips [4 have a portion l1 extending out away from the face of the plastic and doubled over marginal portions 18 spaced from the portion H. The edge IQ of the folded portion I8 is spaced from the plastic sheet as will be obvious from Figures 2 and 3.

The frame has two strips 20, 2| made of sheet metal. It is folded to U-shaped cross section, as will be obvious from the drawing, and has a flange 22 which extends laterally as indicated. The frame may include cross members 23 of shape to conform to the shape of the panel of diffusing material to be used.

In manufacturing the closures the frames are assembled separately from the plastic sheets, the plastic sheets being cut to size, bent to shape, if necessary, and provided with the clips at spaced intervals. To assemble the closure it is merely necessary to slide the closure into place. The edges of the diffusing panel, as well as the clips pass through the U-shaped groove in the frame strips and the spaced portions ll, l8, receive the flanges 22, 22 of the frame. The plastic closure may readily be shifted to the desired position and will remain there owing to the friction of the parts. It, however, is possible for the plastic sheet to stretch, shrink or change its position relative to the frame members without causing any strain which would crack the plastic material and without distortion which would change its appearance. It is also possible to readily remove the closure from the frame, should it be desired to substitute a closure of different color or other ornamental appearance.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What is claimed is:

1. A closure for a fluorescent lighting fixture having an elongated opening of substantial area, comprising a substantially rigid metal frame which includes parallel downwardly opening channel shaped members forming a trackway open at one end, a light diffusing panel of sheet plastic having a substantially different coefiicient of expansion than the frame and having its edges extending upwardly into the frame channels, and

channel walls to prevent buckling of the panel.

2. A closure for a lighting fixture having an opening of substantial area, comprising a substantially rigid metal frame which includes channel shaped members, and a light diffusing panel 15 of sheet plastic having a substantially difierent coefficient of expansion than the frame and having its edges received in the frame channels, and

means for securing the panel in place with the edges thereof in the channels, said means including elements secured to the panel along its edges and having folded channel forming portions, and a continuous flange on each frame member slidably received in the folded portions whereby the panel may expand and contract independently of the frame members.

3. In combination, a light difiusing panel of sheet plastic material and having an edge, a plurality of sheet metal clips secured to the panel near the edge and having folded portions disposed laterally of the face of the panel and forming a guideway parallel with the edge, and a frame member which receives the edge of the panel and the body of the clips and having a flange received in the folded portions of the clips.

JAMES DONNELLY. 

